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Thread: Testing EI - Neg Dev Time - Print Dev Time

  1. #1

    Testing EI - Neg Dev Time - Print Dev Time

    Hello,

    following the discussion about the lack of contrast with the TMAX100 I am doing some test to find out what I might have done wrong and to be more precise in the future.
    Looking up in the forum I've landed on this page (http://www.viewcamera.com/pdf/2006/V...%20Started.pdf) and I am trying to follow this test but I am experiencing some problems...

    Problem number 1:
    When it comes to testing the EI of the particular film the guide suggest to take 6 exposures (by the way why to leave the 6th unexposed!?) rating the film at different speeds (50%, 75%, 100%, 125%, 150% if compared to the declared speed).
    For making my life easier I decide to rate the film according to the options of my meter and therefore I have set: 50, 64, 80, 100, 125, 160 ISO.
    After I have set up the room for the test I noticed that actually, as I am using one flash as source of light and therefore the only thing that I could change for modifing the exposition is the aperture value, setting the proper f/stop it's absolutely not easy!
    As I need to find Zone I I have to stop down 4 stop (therefore multipling by 4 the f/stop that would be suitable for zone V) and these are the numbers that I got:

    ISO------Zone V------Zone I
    50--------5,6----------22,4
    64--------5,63--------22,52
    80--------5,67--------22,68
    100-------8-----------32
    125-------8,03--------32,12
    160-------8,07--------32,28

    How do you set such f/stop on the lens?!
    I have a Schneider Symmar Convertible 150mm/268mm and the f/stop scale it's so tiny that, personally, I think it's impossible to be so precise...

    Is there anything I am missing?
    Any trick!?

    Problem number 2:
    This is much easier...
    When it comes to take the exposure to find the proper developing time for the negative do I have to rate the film with the EI that I found out from the previous step or the manufacterer one? I think that, logically, it should be the EI that I found out doing the previous test but I wanted to double check with you...


    THANK YOU VERY MUCH!

  2. #2
    Land-Scapegrace Heroique's Avatar
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    Re: Testing EI - Neg Dev Time - Print Dev Time

    Quote Originally Posted by Alessandro V. View Post
    Is there anything I am missing? Any trick!?
    Hi Alessandro,

    Can you explain in greater detail why your results are displeasing? And how you produced them? Can you describe the results that would satisfy you?

    All I can tell is that your T-max 100 isn’t contrasty enough. (Or is it your prints?)

    I appreciate your attention to detail – and determining a personal EI is always a good idea – but a simpler solution might be possible, and it might have little to do w/ your original choice of exposure…

    A couple of useful references:

    1) Steve Simmons’ Using the View Camera has a clever section titled “Establishing a Personal Exposure Index” – it’s in the “Zone System” chapter.
    2) See also John Shaw’s Closeups in Nature and its two excellent sections, “Metering” and “Running a Test.”

  3. #3

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    Re: Testing EI - Neg Dev Time - Print Dev Time

    The answer to problem number 2 is to use the EI you came up with in your testing.

    As for #1, I've never heard of doing an EI test with flash. Are you sure that your flash isn't automatically adjusting the intensity of the output as you change your film speeds? If it's doing that either through an "automatic" setting or a "TTL" setting then you're defeating the purpose of the test. I almost never use flash so I'm no expert but I'd suggest making the test outdoors or at least in a well-lit room with a single constant light source.

    Your goal in testing is to find the film speed that produces a density of a Zone I (not II) exposure, which is .08 to .10 log units above film base plus fog. The 6th unexposed sheet is to give you your film base plus fog reading. But if you're not using a densitomter you don't need to worry about the 6th unexposed sheet.

    You don't change apertures to correspond with your meter. You take a meter reading at a particular ISO setting (let's say the manufacturer's speed). An exposure made at any of the various combinations of aperture and shutter given by the meter at that ISO setting would be a Zone V exposures. But you want a Zone I exposure for purposes of the test. So you stop down four stops to get to a Zone I exposure. You make the exposure. Leaving the shutter speed the same you change the ISO setting on the meter to say twice the manufacturer's speed and take another meter reading. The indicated aperture at that shutter speed would produce a Zone V exposure. So you stop down four stops from the indicated aperture for that ISO and make a second exposure. You change the ISO setting on the meter again, to say half the manufacturer's speed. Leaving the shutter speed the same you again stop down four stops to get to a Zone I exposure at that ISO. You make another exposure. You do this until you have five sheets of film, one exposed at the film manufacturer's rated speed and four more at double the speed, half the speed, 75% of the speed, and 25% of the speed.

    Use the same shutter speed for each exposure and change only the aperture to get to Zone I. That way you don't have to worry about your shutter being inaccurate at some speeds. Make the first exposure (the one at the manufacturer's ISO) at a shutter speed fast enough to allow you to stop the aperture down four stops for each of the succeeding four exposures without changing the shutter speed.

    It's been a while since I did my own testing, you only need to do it once for a particular film and developer and I only use one film and one developer so it isn't something I do every day. If I've made any mistakes here my apologies but I'm sure someone will correct me.
    Brian Ellis
    Before you criticize someone, walk a mile in their shoes. That way when you do criticize them you'll be
    a mile away and you'll have their shoes.

  4. #4

    Re: Testing EI - Neg Dev Time - Print Dev Time

    Thank you all for your responses!

    To Heroique...
    I have previously opened another topic about the tmax100 and the unpleasant results I had and during the discussion I've learned about these tests for determining the proper EI of film, dev times, etc. I still did not find out where I have made a mistake but I thought that doing a test might be helpful even just for the future and has an experience.

    To Brian...
    I am shooting with flash because when I will take pictures with my 4x5 I will be in a studio and I'll be shooting with flashes...that's the only reason... :-D
    The flash I am using is a Bowen 1000pro, it is fully manual.
    Thank you for the explanation, that's exactly what I wanted to do!!!
    I mean: keeping the shutter speed always the same (also because using a flash it doesn't matter at all) and modifing the aperture value!
    The problem is that I end up with such f/stops, so close to each other, that it seems impossible to set them on the lens!
    If you take a look at the kind of table I posted I am sure you will understand what I am trying to say (sorry for my bad english).

    Anyway I did not even started with the test because I coulnd't set the f/stop on the lens.

    Thank you!

  5. #5
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    Re: Testing EI - Neg Dev Time - Print Dev Time

    Quote Originally Posted by Alessandro V. View Post
    Problem number 1:
    ...is that your arithmetic is wrong.

    Quote Originally Posted by Alessandro V. View Post
    As I need to find Zone I I have to stop down 4 stop (therefore multipling by 4 the f/stop that would be suitable for zone V) and these are the numbers that I got:

    ISO------Zone V------Zone I
    50--------5,6----------22,4
    64--------5,63--------22,52
    80--------5,67--------22,68
    100-------8-----------32
    125-------8,03--------32,12
    160-------8,07--------32,28

    The table should be more like:

    ISO------Zone V------Zone I
    50--------5,6----------22
    64--------6,3---------24,7
    80--------7,1---------27,7
    100-------8-----------32
    125-------9-----------35,9
    160-------10,1--------40,3

    The last decimal place doesn't matter - you're rounding anyway from a multiplier that's the cube root of the square root of 2; the standard aperture values are themselves approximations.

    More importantly, if you've never done this sort of test before, you should start with full-stop intervals, not 1/3 stop. 1/3 stop changes in negative film are very subtle, especially when you don't know what you're looking for. Minor discrepancies in equipment calibration, limited finesse in setting, and minor inconsistencies in the repeatability of your shutter or flash could easily have effects larger than the differences you're trying to observe, thoroughly confusing your analysis of the results.

  6. #6

    Re: Testing EI - Neg Dev Time - Print Dev Time

    Thank you for correcting my math!
    Actually I literally followed my meter and I multiplied by 4 the number that I got.

    Therefore, supposing I will test the film considering only 1 stop intervals, how many EI should I keep in consideration!?
    For example, for a 100 ISO film, should I test for EI 50, 100, 200 or shall I go further with 25 and 400?!

    Thank you!

  7. #7

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    Re: Testing EI - Neg Dev Time - Print Dev Time

    I was going to suggest tests at EI 12, 25, 50 and 100.

    But since you still aren't happy with your results, it might be best to test at EI 100 and develop longer and hotter. Work up until you start to get test results that agree with the film's rated speed.

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    Re: Testing EI - Neg Dev Time - Print Dev Time

    Quote Originally Posted by Alessandro V. View Post
    For example, for a 100 ISO film, should I test for EI 50, 100, 200 or shall I go further with 25 and 400?!
    I'd go from two stops over to two stops under, or 25 - 50 - 100 - 200 - 400. If you have patience for a sixth sheet, I'd add three stops over, or ISO 12. It may seem like an academic exercise, but if you put in the effort to print all of the negatives, you will learn a whole lot about how B&W film behaves, knowledge that will serve you well even beyond determining a preferred EI for general use.

    Good luck!

  9. #9
    ic-racer's Avatar
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    Re: Testing EI - Neg Dev Time - Print Dev Time

    In terms of the exposure index test, for simplicity, you can just shoot a single Zone I frame at 1/2 the box ISO. (out door lightning, not flash). If it is 0.1 +/- .03 density then you are done and can move on to the development test.

  10. #10
    Steve Smith's Avatar
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    Re: Testing EI - Neg Dev Time - Print Dev Time

    Being lazy, I used a more simple method!

    http://www.freewebs.com/stevesmithphoto/personal.html



    Steve.

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